U.S. patent number 7,597,206 [Application Number 10/908,003] was granted by the patent office on 2009-10-06 for container with one-step closing.
This patent grant is currently assigned to Dart Container Corporation. Invention is credited to Todd W. Atkins, Dean A. Garza.
United States Patent |
7,597,206 |
Atkins , et al. |
October 6, 2009 |
**Please see images for:
( Certificate of Correction ) ** |
Container with one-step closing
Abstract
A clam-shell container comprising a cover hingedly connected to
a tray, with both the cover and tray having cooperating structures
that form a leak-proof seal when the clam-shell container is
closed. The container and cooperating structures are formed such
that the user can effect the formation of the leak-proof seal in a
single step. The creation of the leak-proof seal preferably
corresponds to the closing of the clam-shell container.
Inventors: |
Atkins; Todd W. (Dansville,
MI), Garza; Dean A. (Williamston, MI) |
Assignee: |
Dart Container Corporation
(Mason, MI)
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Family
ID: |
34652256 |
Appl.
No.: |
10/908,003 |
Filed: |
April 25, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050247709 A1 |
Nov 10, 2005 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60521434 |
Apr 26, 2004 |
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Current U.S.
Class: |
220/4.23;
220/324 |
Current CPC
Class: |
B65D
1/36 (20130101); B65D 43/162 (20130101); B65D
85/60 (20130101); B65D 2543/00296 (20130101); B65D
2251/105 (20130101); B65D 2543/00101 (20130101); B65D
2543/00194 (20130101); B65D 85/62 (20130101) |
Current International
Class: |
B65D
6/28 (20060101); B65D 45/16 (20060101) |
Field of
Search: |
;220/4.23,4.22,839,837,836,915.1,DIG.10,810,FOR195,FOR192,818,817
;206/541 ;16/232,231,221 ;292/DIG.17 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3916668 |
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Dec 1989 |
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DE |
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0383677 |
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Aug 1990 |
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EP |
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0 724 530 |
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Aug 1996 |
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EP |
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2606748 |
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May 1988 |
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FR |
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1311617 |
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Mar 1973 |
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GB |
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2160510 |
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Dec 1985 |
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GB |
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2141102 |
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Mar 2008 |
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GB |
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05221476 |
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Aug 1993 |
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JP |
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06115558 |
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Apr 1994 |
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JP |
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8-72909 |
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Mar 1996 |
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JP |
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2002-240842 |
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Sep 2002 |
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JP |
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Primary Examiner: Stashick; Anthony D
Assistant Examiner: Hicks; Robert J
Attorney, Agent or Firm: McGarry Bair PC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from U.S. Provisional Application
No. 60/521,434 filed on Apr. 26, 2004.
Claims
What is claimed is:
1. A one-piece thermoformed container for storing food items,
comprising: a tray comprising a bottom wall from which extends a
peripheral wall to define a recess for storing food items, with the
peripheral wall terminating in a peripheral flange to define an
open top for providing access to the recess; and a cover sized to
close the open top of the tray and comprising a top wall
terminating in a peripheral flange; a hinge connecting the tray and
the cover for relative movement between an opened and a closed
condition such that the tray and cover can be relatively moved to
selectively close the tray with the cover; a first peripheral seal
structure provided on the tray and circumscribing the recess and
having a rear portion adjacent the hinge and a front portion
opposite the rear portion, with the rear portion having a
projection; and a second peripheral seal structure provided on the
cover having a rear portion adjacent the hinge and having a front
portion opposite the rear portion, with the rear portion having a
projection, and the first and second peripheral seal structures
cooperate to form a peripheral seal between the tray and the cover
circumscribing the tray recess in the closed condition; wherein the
cover is vertically offset from the hinge such that the projection
on the rear portion of the second peripheral seal is lower than the
projection of the rear portion of the first peripheral seal in the
opened condition, and the rear portion of the second peripheral
seal structure is wider than the rear portion of the first
peripheral seal structure, such that upon the relative rotation of
the cover and tray, the projection on the rear portion of the
second peripheral seal structure hooks with the projection on the
rear portion of the first peripheral seal structure to form an axis
of rotation therebetween for the subsequent movement of the cover
to the closed condition and upon the application of a compression
force between the front portions of the first and second seal
structures a peripheral seal is formed around the recess to effect
a one-step formation of the peripheral seal and thereby form a
one-step closing container.
2. The one-piece thermoformed container according to claim 1,
wherein the projections on the first and second peripheral seals
are formed by intersecting facets.
3. The one-piece thermoformed container according to claim 2,
wherein one of the first and second seal structures has an overall
polygonal shape when viewed in planform and the other of the first
and second seal structures has an overall trapezoidal shape when
viewed in planform.
4. The one-piece thermoformed container according to claim 3,
wherein the polygonal shape is a rectangle.
5. The one-piece thermoformed container according to claim 1,
wherein the front portion of the first peripheral seal structure is
located forward of the front portion of the second peripheral seal
structure as the container is brought into the closed condition to
require the relative deflection between the front portions to move
the container into the closed condition.
6. The one-piece thermoformed container according to claim 5,
wherein both the first and second peripheral seal structures
comprise opposing side portions extending between the corresponding
rear portion and front portion, with at least one of the side
portions of the first peripheral seal structure having a crown that
extends exteriorly of the corresponding side portion of the second
peripheral seal structure to require the relative deflection of the
at least one of the side portions of the first seal structure and
the corresponding side portion of the second seal structure to move
the container into the closed condition.
7. The one-piece thermoformed container according to claim 6,
wherein the circumference of the first seal structure is
substantially the same as the circumference of the second seal
structure.
8. The one-piece thermoformed container according to claim 6,
wherein one of the first and second seal structures comprises a
peripheral shoulder and the other of the first and second seal
structures comprises a sealing facet against which the shoulder
presses when the cover is in the closed condition to form the
substantially liquid-tight seal about the periphery of the
recess.
9. The one-piece thermoformed container according to claim 8,
wherein a portion of the shoulder deflects against the sealing
facet.
10. The one-piece thermoformed container according to claim 8,
wherein the shoulder comprises a flat extending along at least one
side portion of the one of the first and second seal
structures.
11. The one-piece thermoformed container according to claim 10,
wherein the one of the first and second peripheral seal structures
comprises a first peripheral facet opposite the shoulder and the
other of the first and second peripheral seal structures comprises
a second peripheral facet opposite the sealing facet and first and
second peripheral facets abut each other to form a second
peripheral substantially liquid-tight seal about the recess.
12. The one-piece thermoformed container according to claim 11,
wherein the shoulder, sealing facet, first facet, and second facet
are configured such that sealing facet and second facet apply
opposing pressing forces to the shoulder and first facet,
respectively.
13. A one-piece thermoformed container for storing food items,
comprising: a tray comprising a bottom wall from which extends a
peripheral wall to define a recess for storing food items, with the
peripheral wall terminating in a peripheral flange to define an
open top for providing access to the recess; and a cover sized to
close the open top of the tray and comprising a top wall
terminating in a peripheral flange; a hinge connecting the tray and
the cover for relative movement between an opened and a closed
condition such that the tray and cover can be relatively moved to
selectively close the tray with the cover; a first peripheral seal
structure provided on the tray and circumscribing the recess and
having a rear portion adjacent the hinge and a front portion
opposite the rear portion, with the rear portion having a
projection; a second peripheral seal structure provided on the
cover having a rear portion adjacent the hinge and having a front
portion opposite the rear portion, with the rear portion having a
projection, and the first and second peripheral seal structures
cooperate to form a peripheral seal between the tray and the cover
circumscribing the tray recess in the closed condition; a bar lock
comprising at least one complementary projection and recess, with
the projection extending from at least one of the first and second
peripheral seal structure and the recess extending below the other
of the first and second peripheral seal structure such that
projection is received within the recess in the closed condition;
and wherein the cover is vertically offset from the hinge such that
the projection on the rear portion of the second peripheral seal is
lower than the projection of the rear portion of the first
peripheral seal in the opened condition, and the rear portion of
the second peripheral seal structure is wider than the rear portion
of the first peripheral seal structure, such that upon the relative
rotation of the cover and tray, the projection on the rear portion
of the second peripheral seal structure hooks with the projection
on the rear portion of the first peripheral seal structure to form
an axis of rotation therebetween for the subsequent movement of the
cover to the closed condition and upon the application of a
compression force between the projection and recess a peripheral
seal is formed around the recess to effect a one-step formation of
the peripheral seal and thereby form a one-step closing
container.
14. The one-piece thermoformed container according to claim 13,
wherein the projections on the first and second peripheral seals
are formed by intersecting facets.
15. The one-piece thermoformed container according to claim 13,
wherein one of the first and second peripheral seal structures
comprises a deformable rounded shoulder and the other of the first
and second peripheral seal structures comprises a sealing facet
against which the shoulder deforms when the cover is in the closed
condition to form a substantially liquid-tight seal between the
shoulder and the sealing facet.
16. The one-piece thermoformed container according to claim 15,
wherein a portion of the shoulder deflects against the sealing
facet.
17. The one-piece thermoformed container according to claim 15,
wherein the one of the first and second peripheral seal structures
comprises a first peripheral facet opposite the shoulder and the
other of the first and second peripheral seal structures comprises
a second peripheral facet opposite the sealing facet and the first
and second peripheral facets abut each other to form a second
peripheral substantially liquid-tight seal about the recess.
18. The one-piece thermoformed container according to claim 17,
wherein the shoulder, sealing facet, first facet, and second facet
are configured such that sealing facet and second facet apply
opposing pressing forces to the shoulder and first facet,
respectively.
19. The one-piece thermoformed container according to claim 18
wherein each of the first and second peripheral seal structures
comprise a pair of opposing side portions.
20. The one-piece thermoformed container according to claim 19,
wherein the shoulder along the pair of opposing side portions of
the one of the first and second peripheral seal structures
comprises a flat.
21. The one-piece thermoformed container according to claim 13,
wherein each of the first and second peripheral seal structures
comprises a rear portion near the hinge.
22. The one-piece thermoformed container according to claim 21,
wherein the hinge is configured to locate the rear portion of the
second peripheral seal structure relative to the rear portion of
the first peripheral seal structure such that as the cover is
rotated from the opened to the closed condition, the rear portion
of the second peripheral seal structure contacts the rear portion
of the first seal structure to form an axis of rotation for the
subsequent movement of the cover to the closed condition.
23. The one-piece thermoformed container according to claim 22,
wherein the hinge is further configured to locate the rear portion
of the second peripheral seal structure below the rear portion of
the first peripheral seal structure.
24. The one-piece thermoformed container according to claim 22,
wherein the rear portion of the second peripheral seal structure is
wider than the rear portion of the first peripheral seal
structure.
25. The one-piece thermoformed container according to claim 21,
wherein each of the first and second peripheral seal structures
comprises a front portion opposite the rear portion.
26. The one-piece thermoformed container according to claim 25, and
further comprising a pair of spaced indicia in proximity to the
front portion and indicating the location where a compressive force
can be applied to effect the cooperation of the first and second
peripheral seal structures and form the substantially liquid-tight
seal.
27. The one-piece thermoformed container according to claim 26,
wherein each spaced indicia comprises a mating projection and
recess provided on one of the cover and tray, respectively.
28. The one-piece thermoformed container according to claim 27,
wherein the projection and recess are configured to lock the cover
to the tray when mated.
29. The one-piece thermoformed container according to claim 13,
wherein each of the first and second peripheral seal structures has
a front portion, a rear portion, and opposing side portions
extending between the front and rear portion, with the first
peripheral seal structure having a trapezoidal shape and the second
peripheral seal structure having a rectangular shape.
30. The one-piece thermoformed container according to claim 29,
wherein the rear portion of the first peripheral seal structure is
wider the front portion of the first peripheral seal structure.
31. The one-piece thermoformed container according to claim 30,
wherein the rear portion of the first peripheral seal structure is
wider than the rear portion of the second peripheral seal
structure.
32. The one-piece thermoformed container according to claim 31,
wherein the side portions of the second peripheral seal structure
have a crown that is deflected by the corresponding side portions
of the first peripheral seal structure when the cover is moved into
the closed condition.
33. The one-piece thermoformed container according to claim 32,
wherein the front portion of the second peripheral seal structure
is shaped such that it is deflected by the front portion of the
first peripheral seal structure when the cover is moved into the
closed condition.
34. The one-piece thermoformed container according to claim 33,
wherein the circumference of the first and second peripheral seal
structures is approximately equal.
35. A one-piece thermoformed container for storing food items,
comprising: a tray comprising a bottom wall from which extends a
peripheral wall to define a recess for storing food items, with the
peripheral wall terminating in a peripheral flange to define an
open top for providing access to the recess; and a cover sized to
close the open top of the tray and comprising a top wall
terminating in a peripheral flange; a hinge connecting the tray and
the cover for relative movement between an opened and a closed
condition such that the tray and cover can be relatively moved to
selectively close the tray with the cover; a first peripheral seal
structure provided on the tray and circumscribing the recess and
having a rear portion adjacent the hinge and a front portion
opposite the rear portion, with the rear portion having a
projection; and a second peripheral seal structure provided on the
cover having a rear portion adjacent the hinge and having a front
portion opposite the rear portion, with the rear portion having a
projection, and the first and second peripheral seal structures
cooperate to form a peripheral seal between the tray and the cover
circumscribing the tray recess in the closed condition; wherein the
cover is vertically offset from the hinge such that the projection
on the rear portion of the second peripheral seal is lower than the
projection of the rear portion of the first peripheral seal in the
opened condition, such that upon the relative rotation of the cover
and tray, the projection on the rear portion of the second
peripheral seal structure hooks with the projection on the rear
portion of the first peripheral seal structure to form an axis of
rotation therebetween for the subsequent movement of the cover to
the closed condition and upon the application of a compression
force between the front portions of the first and second seal
structures a peripheral seal is formed around the recess to effect
a one-step formation of the peripheral seal and thereby form a
one-step closing container.
Description
FIELD OF THE INVENTION
The invention relates to a recloseable clam-shell type container
comprising a tray and cover hingedly mounted together. The
invention further relates to a recloseable clam-shell type
container wherein the cover can be closed relative to the tray and
in one step. The invention also relates to a leak-proof seal being
formed between the tray and the cover upon closing.
DESCRIPTION OF THE PROBLEM
Clam-shell type containers are commonly used in the food industry
for transporting the food home by the consumer, especially in the
ready-to-eat food industry and in the restaurant industry for
packaging leftovers. The clam-shell food containers are very
convenient in that they comprise a cover that is hingedly mounted
to a tray, which provides for convenient storage by the food
service provider and convenient operation by the user.
Clam shell containers are generally thermoformed from two types of
material. One type of material is foam made by expanding a suitable
thermoplastic, such as polystyrene. Another type of material is
made from a non-expanded thermoplastic, such as oriented
polystyrene (OPS) or polyethelyenetheraphalate (PET). The foam
containers are best suited for applications where the insulating
characteristics of the foam are of a high priority, such as when
the food is to be maintained at temperature prior to serving. The
non-expanded thermoplastic containers are best suited when forming
a seal between the cover and the tray to prevent leakage is a high
priority, such as when leftovers are being taken home from a
restaurant. The non-expanded materials are much more suitable than
the expanded materials for being easily formed into the cooperating
complex shapes necessary for the cover and the tray to form a
leak-proof seal when closed.
The leak-proof seal is generally formed by cooperating structures
extending about the peripheral of the cover and the tray and must
be snap-fit together to form the leak-proof seal. Since most
clam-shell containers are multi-sided, most often
rectangularly-shaped, with more sides than the user has hands, to
form the leak-proof seal, the user must snap the cooperating
structures along each of the sides, resulting in a multi-step
closing process. Most consumers find the multi-step closing very
inconvenient. More troubling is that the more steps that are
required to form the leak-proof seal, the more likely it is that
the consumer will forget one of the steps or improperly perform one
of the steps, resulting in an improperly formed seal and permitting
the leaking of the contents from the container.
It is desirable to have a clam-shell type container with a one-step
closing to effect the creation of the leak-proof seal.
SUMMARY OF THE INVENTION
The invention relates to a one-piece thermoformed container for
storing food items. The container comprises a tray defining a
recess for storing food items and defining an open top for
providing access to the recess, and a cover sized to close the open
top of the tray. A hinge connects the tray and the cover for
relative movement between an opened and a closed condition such
that the tray and cover can be relatively moved to selectively
close the tray with the cover. A first seal structure is provided
on one of the tray and cover and has a polygonal shape, and a
second seal structure provided on the other of the tray and cover
and has an overall trapezoidal shape with a rear portion near the
hinge and a front portion opposite the rear portion. The first and
second seal structures cooperate to form a substantially
liquid-tight peripheral seal between the tray and the cover about
the tray recess when the tray and cover are in the closed
condition, and the trapezoidal shape and polygonal shape are
configured such that that application of a compression force
between the first and second seal structures at spaced locations on
the front portion of the second seal structure is the only step
needed to complete the formation of the liquid-tight seal.
The polygonal shape can comprise a rear portion and front portion
and the first and second seal structures can be shaped such that at
least a portion of the front portion of the polygonal shape is
located forward of the front portion of the trapezoidal shape and
requiring the relative deflection between the front portions to
move the cover into the closed condition. Both the polygonal shape
and the trapezoidal shape can comprise opposing side portions
extending between the rear portion and front portion, with at least
one of the side portions of the polygonal shape having a crown that
extends exteriorly of the corresponding side portion of the
trapezoidal shape to require the relative deflection of the at
least one of the side portions of the polygonal shape and the
corresponding side portion of the trapezoidal shape to move the
cover into the closed condition. The circumference of the first
seal structure can be substantially the same as the circumference
of the second seal structure.
The one of the first and second seal structures can comprise a
peripheral shoulder and the other of the first and second seal
structures can comprise a sealing facet against which the shoulder
presses when the cover is in the closed condition to form the
substantially liquid-tight seal about the periphery of the recess.
A portion of the shoulder can deflect against the sealing facet.
The shoulder can comprise a flat extending along at least one side
portion of the one of the first and second seal structures. The one
of the first and second seal structures can comprise a first
peripheral facet opposite the shoulder and the other of the first
and second seal structures can comprise a second peripheral facet
opposite the sealing facet and first and second peripheral facets
can abut each other to form a second peripheral substantially
liquid-tight seal about the recess. The shoulder, sealing facet,
first facet, and second facet can be configured such that sealing
facet and second facet apply opposing pressing forces to the
shoulder and first facet, respectively.
The hinge can be configured to locate the rear portion of the
second seal structure relative to the rear portion of the first
seal structure such that as the cover is rotated from the opened to
the closed condition, the rear portion of the second seal structure
contacts the rear portion of the first seal structure to form an
axis of rotation for the subsequent movement of the cover to the
closed condition. The hinge can be further configured to locate the
rear portion of the second seal structure below the rear portion of
the first seal structure.
The rear portion of the second seal structure is wider than the
rear portion of the first seal structure. The polygonal shape and
the trapezoidal shape can comprise rear corners at the junction of
the side portions with the rear portion and front corners at the
junction of the side portions with the front portions. The rear
corners of the trapezoidal shape can have a radius greater than the
rear corners of the polygonal shape.
The polygonal shape can be a rectangle. The tray can comprise a
bottom wall and a peripheral wall extending upwardly from the
bottom wall to define the recess, with the first seal structure
extending from the peripheral wall. The peripheral wall can
terminate in a peripheral flange and the first seal structure
extends from the peripheral flange. The cover can comprise a top
wall and a peripheral wall extending downwardly from the top wall
and terminating in a peripheral flange, with the second seal
structure extending from the peripheral flange of the cover.
A pair of spaced indicia can be provided to indicate the location
for applying the compressive force. Each spaced indicia can
comprise a mating projection and recess provided on one of the
cover and tray, respectively. The projection and recess are
configured to lock the cover to the tray when mated.
In another aspect, the invention relates to a one-piece
thermoformed container for storing food items. The container
comprises a tray defining a recess for storing food items and
defining an open top for providing access to the recess and a cover
sized to close the open top of the tray. A hinge connects the tray
and the cover for relative movement between an opened and a closed
condition such that the tray and cover can be relatively moved to
selectively close the tray with the cover. A first seal structure
is provided on one of the tray and cover and a second seal
structure is provided on the other of the tray and cover, with the
first and second seal structures cooperating with each other to
form a peripheral seal between the cover and the tray about the
recess when the cover is in the closed condition. The one of the
first and second seal structures can comprise a peripheral shoulder
and the other of the first and second seal structures can comprises
a sealing facet against which the shoulder abuts when the cover is
in the closed condition to form the substantially liquid-tight seal
about the periphery of the recess.
A portion of the shoulder can deflect against the sealing facet.
The one of the first and second seal structures can comprise a
first peripheral facet opposite the shoulder and the other of the
first and second seal structures can comprise a second peripheral
facet opposite the sealing facet and the first and second
peripheral facets abut each other to form a second peripheral
substantially liquid-tight seal about the recess. The shoulder,
sealing facet, first facet, and second facet are configured such
that sealing facet and second facet apply opposing pressing forces
to the shoulder and first facet, respectively.
Each of the first and second seal structures can comprise a pair of
opposing side portions. The shoulder along the pair of opposing
side portions of the one of the first and second seal structures
can comprise a flat.
Each of the first and second seal structures can comprise a rear
portion near the hinge. The hinge is configured to locate the rear
portion of the second seal structure relative to the rear portion
of the first seal structure such that as the cover is rotated from
the opened to the closed condition, the rear portion of the second
seal structure contacts the rear portion of the first seal
structure to form an axis of rotation for the subsequent movement
of the cover to the closed condition.
The hinge can be further configured to locate the rear portion of
the second seal structure below the rear portion of the first seal
structure. The rear portion of the second seal structure can be
wider than the rear portion of the first seal structure.
Each of the first and second seal structures can comprise a front
portion opposite the rear portion. A pair of spaced indicia can be
located in proximity to the front portion to indicate the location
where a compressive force can be applied to effect the cooperation
of the first and second seal structures and form the substantially
liquid-tight seal. Each spaced indicia can comprise a mating
projection and recess provided on one of the cover and tray,
respectively. The projection and recess can be configured to lock
the cover to the tray when mated.
Each of the first and second seal structures can have a front
portion, a rear portion, and opposing side portions extending
between the front and rear portion, with the first seal structure
having a trapezoidal shape and the second seal structure having a
rectangular shape. The rear portion of the first seal structure can
be wider the front portion of the first seal structure. The rear
portion of the first seal structure can be wider than the rear
portion of the second seal structure. The side portions of the
second seal structure can have a crown that is deflected by the
corresponding side portions of the first seal structure when the
cover is moved into the closed condition. The front portion of the
second seal structure can be shaped such that it is deflected by
the front portion of the first seal structure when the cover is
moved into the closed condition. The circumference of the first and
second seal structures can be approximately equal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a clam-shell container according to
the invention comprising a cover hingedly mounted to a tray, with
the cover in an open position.
FIG. 2 is a perspective view of the clam-shell container of FIG. 1
with the cover in a closed position.
FIG. 3 is a longitudinal side view of the clam-shell container of
FIG. 1.
FIG. 4 is a top view of the clam-shell container of FIG. 1.
FIG. 5 is an enlarged sectional view of the cover taken along line
5-5 of FIG. 4 and illustrating in detail the cross-sectional shape
of a cover seal structure.
FIG. 6 is an enlarged sectional view of the tray taken along line
6-6 of FIG. 4 and illustrating in detail the cross-sectional shape
of a tray seal structure along the front and back sides.
FIG. 7 is an enlarged sectional view of the tray taken along line
7-7 of FIG. 4 and illustrating in detail the cross-sectional shape
of a tray seal structure along the lateral sides of the clam-shell
container.
FIG. 8 is a broken and enlarged side view of the tray of the
clam-shell container of FIG. 1 and illustrating in detail the
portion of the seal structure along the lateral sides of the
clam-shell container.
FIG. 9 is a schematic illustrating the interaction between the
cover seal structure and the tray seal structure along the lateral
sides of the clam-shell container in the closed position.
FIG. 10 is a schematic illustrating the peripheral shape of the
tray seal structure and the corresponding dimensions.
FIG. 11 is a schematic illustrating the peripheral shape of the
cover seal structure and the corresponding dimensions.
FIG. 12 is a schematic illustrating the peripheral shapes of the
tray and seal structures of FIGS. 10 and 11 in overlying
relationship.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-4 illustrate a clam-shell container 10 comprising a cover
12 and a tray 14, which are connected by a hinge 16. The clam-shell
container 10 is operable between an open condition (FIG. 1) and a
closed condition (FIG. 2) by rotating the cover 12 about the hinge
16 from an open position (FIG. 1) to a closed position (FIG. 2).
The cover 12, tray 14, and hinge 16 are preferably integrally
formed from a single piece of material in a well known
thermoforming process. Suitable materials for the clam-shell
container 10 include OPS and PET.
The cover 12 comprises a top 20 from which extends a peripheral
sidewall 22, which terminates in a peripheral flange 24 and from
which extends a cover seal structure 26. As illustrated, the top 20
comprises a substantially planar portion that steps down to the
peripheral sidewall 22. However, the top 20 could have a more
complex relief if desired.
The peripheral sidewall 22 is illustrated as having a generally
vertical portion that transitions to a horizontal portion at the
junction with the top 20. Multiple ribs 30 are provided in the
peripheral sidewall 22 for strengthening. As illustrated, the
peripheral sidewall 22 defines a rectangular shape comprising
opposing front and rear sides 32, 34 and opposing lateral sides 36,
38, with the rear side 34 being located adjacent to and parallel
with the hinge 16.
A pair of bar lock recesses 42 are formed in the peripheral flange
24. For the four-sided configuration illustrated in FIGS. 1-4, the
bar lock recesses 42 are preferably located at the junction of the
lateral sides 36, 38 with the front side 32. A pair of pull tabs 44
extend from the cover seal structure 26. The pull tabs 44 are
preferably located along the cover seal structure 26 such that they
correspond to the bar lock recesses 42 to aid in the opening of the
clam-shell container 10 from the closed and sealed condition.
The tray 14 has the same general configuration as the cover 12.
That is, the tray 14 comprises a bottom 50 from which extends a
peripheral sidewall 52, which terminates in a peripheral flange 54
and from which extends a tray seal structure 56. As illustrated,
the bottom 50 comprises a substantially planar portion that steps
down to the peripheral sidewall 52. Like the top 20, the bottom 50
could have a more complex relief if desired.
The peripheral sidewall 52 is illustrated as having a generally
vertical portion that transitions to a horizontal portion at the
junction with the bottom 50. Multiple ribs 60 are provided in the
peripheral sidewall 52 for strengthening. As illustrated, the
peripheral sidewall 52 defines a rectangular shape comprising
opposing front and rear sides 62, 64 and opposing lateral sides 66,
68, with the rear side 64 being located adjacent to and parallel
with the hinge 16. In essence, the hinge 16 is formed in the
material connecting the rear sides of the cover 12 and tray 14.
A pair of bar lock projections 72 are formed in the peripheral
flange 54. For the four-sided configuration illustrated in FIGS.
1-4, the bar lock projections 72 are preferably located at the
junction of the lateral sides 66, 68 with the front side 62, which
will cause the bar lock projections 72 to be aligned with and
received in the bar lock recesses 42 of the cover 12 when the
clam-shell container 10 is in the closed condition. In this manner,
the bar lock recess 42 and the bar lock projections collectively
form a pair of bar locks for keeping the clam-shell container
locked in the closed condition.
It should be noted that bar locks are well known for this purpose
in the art. The particular type of bar lock used is not germane to
the invention. In fact, the bar locks are not even necessary for
the invention as the cooperating cover and tray seal structures 26,
56 are sufficient to hold the clam-shell container in the closed
condition. Since users have become accustomed to the bar locks for
identifying the location where the user should press the cover 12
and tray 14 to effect closure, the bar locks are provided as a
visual indication for where the user needs to snap close the cover
and tray seal structures 26, 56. The bar locks could be replaced
with some other visual indication for the snap close location.
While the bar locks could be eliminated, the preferred embodiment
does use the bar locks because they provide extra "holding power"
in keeping the container closed. The holding power they provide is
especially noticeable when the closed container has force applied
to the sides. The bar locks help resist unintended openings when
side force is applied.
A pair of pull tabs 74 extend from the cover seal structure 26. The
pull tabs 44 are preferably located along the cover seal structure
such that they correspond to the bar lock recesses to aid in the
opening of the clam-shell container 10 from the closed and sealed
condition.
The specific structure of the cover and tray seal structures 26, 56
will now be examined in greater detail. FIG. 5 illustrates the
cross-sectional shape of the cover seal structure 26, which
comprises three major annular facets 80, 82, and 84. A peripheral
lip 86 extends laterally from the third facet 84. The first and
second facets 80, 82 define an annular channel 88. The first facet
80 extends from peripheral flange 24 at a 45 degree angle relative
to the vertical for a distance of 0.095 inches. The second facet 82
extends from the first facet 80 at a -20 degree angle relative to
the vertical for 0.106 inches. The third facet 84 extends from the
second facet 82 at and angle of 45 degrees relative to the vertical
for 0.103 inches. The cross section of the cover seal structure is
consistent around the periphery of the cover 12.
FIGS. 6-8 illustrate the cross-sectional shape of the tray seal
structure. Unlike the cover 12, the tray seal structure 56 has two
distinct cross-sectional shapes. FIG. 6 illustrates one of the
cross-sectional shapes of the tray seal structure, which is
primarily located along the front and rear sides 62, 64. This
cross-sectional shape of the tray seal structure comprises two
annular facets 90, 92 and a rounded portion 94. The first facet
extends at an angle of -45 degrees from the vertical for a distance
of 0.095 inches. The second facet extends at an angle of 20 degrees
from the vertical for a distance of 0.106 inches. The rounded
portion 94 spans a length of 0.103 inches. A peripheral lip 96
extends from the first facet 90.
FIGS. 7 and 8 illustrate the second cross-sectional shape for the
tray seal structure 56. The second cross-sectional shape of the
tray seal structure differs from the first cross-sectional shape of
FIG. 6 in that a third facet 98 extends between the second facet 92
and the rounded portion 94. The third facet 98 is generally
vertical. The addition of the third facet 98 necessarily shortens
the extent of the rounded portion 94 and the second facet 92 as
described in FIG. 6. As best seen in FIG. 8, the third facet 98 is
essentially a flat that extends along a portion of the tray seal
structure corresponding to the lateral sides 66, 68. The addition
of the vertically-shaped third facet 98 has been found to improve
the ability of the cover seal structure 26 to snap past tray seal
structure 56 upon closing of the container.
The interaction between the cover and tray seal structures 26, 56
when the clam-shell container 10 is in the closed condition is
shown in FIG. 9. In the closed condition, there are two contact
points between the cover and tray seal structures 26, 56. First,
the rounded portion 94 of the tray seal structure 56 is located
within the groove 88 such that it abuts the first facet 80 of the
cover seal structure 26. In this manner, the rounded portion 94
functions much like an O-ring-like seal about the periphery of the
cover 12 and tray 14. Second, the second facet 92 of the tray seal
structure 56 abuts the second facet 82 of the cover seal structure
26. Similar contact between the cover seal structure 26 and the
tray seal structure 56 exists along their entire interface.
Preferably, the spatial relationship between the first and second
facets 80, 82 forming the groove 88 are such that they apply a
compressive force across the rounded portion 94 and the second
facet 92. This compressive force can be created by slightly
undersizing the groove 88 and relying on the inherently resiliency
of the material forming the first and second facets 80, 82.
FIGS. 10-12 illustrate the peripheral dimensions of the cover seal
structure 26 and the tray seal structure 56 and their interaction
when the clam-shell container 10 is in the closed condition. It
should be noted that FIGS. 10-12 describe the "mold" side of the
container and do not account for material thickness. When material
thickness is accounted for the interference between the seal
structures 26, 56 will be greater than illustrated.
FIG. 10 illustrates the peripheral dimensions of the tray seal
structure 56. As can be seen, the tray seal structure generally
follows the shape of the front 62, rear 64, and lateral sides 66,
68 of the tray 14 and comprises corners 100 connecting front 102,
rear 104, and lateral 106, 108 portions of the tray seal structure
56. The corners have a radius of curvature of 0.750 inches, which
is substantially smaller than prior art containers. The rear
portion 104 is generally straight. The front portion 102 has a
radius of curvature of 25.317 inches. The lateral portions 106, 108
each have a radius of curvature of 35.170 inches. With this
configuration, the maximum length of the tray seal structure is
7.580 inches and the maximum width is 8.025 inches.
FIG. 11 illustrates the peripheral dimensions of the cover seal
structure 26. Like the tray seal structure 56, the cover seal
structure 26 generally follows the shape of the front 32, rear 34,
and lateral sides 36, 38 of the cover 12 and comprises corners 110
connecting the front 112, rear 114, and lateral 116, 118 portions
of the cover seal structure 26. The corners 110 have a radius of
curvature of 0.763 inches, which is greater than the radius of
curvature for the corners 100 of the tray seal structure 56 but
still substantially smaller than prior art containers and greater.
The rear portion 114 has a radius of curvature of 124.197. The
front portion 112 has a radius of curvature of 25.295 inches. The
lateral portions 116, 118 have a radius of curvature of 35.893
inches. With this configuration, the maximum length of the cover
seal structure is 7.680 inches (same as the tray seal structure)
and the maximum width is 8.091 inches (greater than the tray seal
structure).
It can readily be seen that the cover seal structure 26 is wider
along the rear portion 114 (7.846 inches) than the front portion
112 (7.816 inches). In this manner, the cover seal structure 26 can
be thought of as having an overall trapezoidal shape with the wide
portion being at the rear portion and the narrower portion being at
the front portion.
The overall trapezoidal shape is not a true trapezoidal shape in
that the lateral portions 116, 118 do not taper continuously from
the rear portion 114 to the front portion 112. Instead, the lateral
portions 116, 118 are arcuate and have a crown 117, 119, which lies
closer to the front portion 112 than to the rear portion 114. From
the rear portion 114 to the crowns 117, 119, the lateral portions
116, 118 actually diverge, instead of taper. From the crowns 117,
119 to the front portion 112 the lateral portions 116, 118 taper,
with the magnitude of the taper being greater than the magnitude of
the divergence, resulting in the overall trapezoidal shape.
The rear portion 114 of the cover seal structure curves into the
interior of the cover whereas the front portion 112 and lateral
portions 116, 118 curve away from the interior of the cover. In
other words, when viewing from the interior of the cover, the rear
portion 114 is convex and the front portion 112 and lateral
portions 116, 118 are concave. The convex shape of the rear portion
114 aids in the positioning and coupling of the cover 12 to the
tray 12 by improving the engagement of the cover rear portion 114
with the tray rear portion 104 upon closing.
FIG. 12 illustrates the dimensional differences of the tray and
cover seal structures 56, 26 by laying them on top of each other.
The corners 110 of the cover 12 are slightly larger than the
corners 100 of the tray 14. While the front 112 and rear 114
portions of the cover 12 lie within the periphery of the tray 14,
the lateral portions 116, 118 of the cover 12 lie exteriorly of the
lateral portions 106, 108 of the tray.
It is worth noting that while the shapes of the cover and tray seal
structures 26, 56 are different they both have approximately the
same circumference. For example, the cover seal structure 26 has a
circumference of 29.350 inches and the tray seal structure has a
circumference of 29.232 inches.
In the prior art containers, there was a gap of approximately 0.022
inches between the tray seal structure 56 and the cover seal
structure 26. FIG. 12 shows how this gap has changed with the
current container. The gap along the lateral portions near the rear
corners is 0.048 inches. The gap along the lateral portions near
the front corners is 0.023 inches. Both of these dimensions are
greater than the prior gap. The gap along the front portion near
the corner is -0.022 inches. The negative gap results from the
front portion of the tray seal structure extending beyond the front
portion of the cover seal structure.
The shape of the cover and tray seal structures 26, 56 and spatial
relationships resulting from the dimensional differences in the
cover and tray seal structures 26, 56 are helpful in forming the
leak-proof seal and providing the one-step closure. For purposes of
the description, it is presumed that the cover 12 has been rotated
about the hinge 16 until the cover 12 overlies the tray 14. Because
the cover 12 is vertically offset from the tray 14, along the rear
portions 104, 114 the second facet 82 of the cover seal structure
26 will necessarily be adjacent to and beneath the second facet of
the tray seal structure 56. Conceptually, this can be thought of as
the rear portion 114 of the cover sealing structure 26 being hooked
to the rear portion 104 of the of the tray sealing structure 56. In
addition to the vertical offset, the concave shape of the rear
portion 114 of the cover aids in the engagement between the cover
rear portion 114 and the tray rear portion 104. The convex shape
creates a nose that is rotated beneath the rear portion 104 of the
tray seal structure 56 upon rotation of the cover 12 and helps
guide the remainder of the rear portion 114 beneath the rear
portion 104.
From this starting position, the user can move the clam-shell
container into a sealed and closed condition with a single step by
pressing the bar lock projections 72 into the bar lock recesses 42.
If the bar locks are not used, the user would just press in the
same area. This action by the user causes the cover seal structure
26 to pivot about the tray seal structure 56 along the hooked rear
portions 104, 114. As the cover seal structure 26 pivots, the
corners 100 of the tray 14 are easily received with the
larger-sized corners 110 of the cover 12. Similarly, the lateral
portions 106, 108 are easily received within the lateral portions
116, 118. The flat created by the third facet 98 along the lateral
portions 106, 108 of the tray seal structure 56 enhances the
movement of the lateral portions 116, 118 of the cover seal
structure 26 past the lateral portions 106, 108 of the tray seal
structure 56.
This easy receipt of the tray seal structure 56 into the downwardly
pivoting cover seal structure 26 continues until the corners 100
along the front portion 102 of the tray 16 are encountered. Since
these corners 100 of the tray 16 and the front portion 102 of the
tray 102 lie outside the periphery of the corresponding portions of
the cover seal structure 26, the corresponding corners 110 and
front portion 112 of the cover seal structure 26 must be deflected
over the tray seal structure 56. Fortunately, the force applied the
by user to the bar locks is sufficient for the necessary deflection
to complete the encircling of the tray seal structure 56 by the
cover seal structure 26 by forcing the corners 110 of the cover
seal structure 26 and the front portion 112 over the corresponding
portions of the tray seal structure 56.
Given that the cover and tray seal structures 26, 56 are made from
resilient material and have a different shape but approximately the
same circumference, the encircling of the tray seal structure 56 by
the cover seal structure 26 essentially causes the cover and tray
seal structures to conform to essentially the same common shape
upon closing, resulting in the rounded portion 94 of the tray seal
structure 56 filling in the channel 88 in the cover seal structure
26 and bearing against the first facet 80 to form a continuous
O-ring-type seal about the periphery of the cover 12 and tray 14.
Similarly, the second facet 92 of the tray seal structure 56 bears
against the second facet 82 of the cover seal structure 26 to form
a second peripheral seal.
The ability for the user to close and seal the cover 12 to the tray
14 in one step is a great improvement over the prior art
containers, which required multiple steps to effect the closing and
seal creation. Several specific changes were made to the container
to effect the one-step closing and sealing. The radius of the
corners of the sealing structure, especially the corners along the
hinge, was substantially reduced resulting in an increase of the
hinge length. That is, the hinge extends along a greater extent of
the container. The cover is vertically offset from the tray. This
is done by locating the cover peripheral lip below the sheet line
as illustrated in FIG. 3. The cover has an overall trapezoidal
configuration. Finally, the circumference of the cover and seal
structures were kept approximately the same even though they had
different shapes.
* * * * *